package com.chy.gulimall.seckill.service.impl;

import com.alibaba.csp.sentinel.annotation.SentinelResource;
import com.alibaba.csp.sentinel.slots.block.BlockException;
import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.TypeReference;
import com.baomidou.mybatisplus.core.toolkit.IdWorker;
import com.chy.common.to.mq.SeckillOrderTo;
import com.chy.common.utils.R;
import com.chy.common.vo.MemberRespVo;
import com.chy.gulimall.seckill.feign.CouponFeignService;
import com.chy.gulimall.seckill.feign.ProductFeignService;
import com.chy.gulimall.seckill.interceptor.LoginUserInterceptor;
import com.chy.gulimall.seckill.service.SeckillService;
import com.chy.gulimall.seckill.to.SeckillSkuRedisTo;
import com.chy.gulimall.seckill.vo.SeckillSessionWithSkus;
import com.chy.gulimall.seckill.vo.SkuInfoVo;
import lombok.extern.slf4j.Slf4j;
import org.apache.commons.lang.StringUtils;
import org.redisson.api.RSemaphore;
import org.redisson.api.RedissonClient;
import org.springframework.amqp.rabbit.core.RabbitTemplate;
import org.springframework.beans.BeanUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.core.BoundHashOperations;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Service;

import java.util.*;
import java.util.concurrent.TimeUnit;
import java.util.regex.Pattern;
import java.util.stream.Collectors;

@Slf4j
@Service
public class SeckillServiceImpl implements SeckillService {

    @Autowired
    private CouponFeignService couponFeignService;
    @Autowired
    private ProductFeignService productFeignService;
    @Autowired
    private StringRedisTemplate redisTemplate;
    @Autowired
    private RedissonClient redissonClient;
    @Autowired
    private RabbitTemplate rabbitTemplate;

    public final String SESSIONS_CACHE_PREFIX = "seckill:sessions:";
    public final String SKUKILL_CACHE_PREFIX = "seckill:skus";
    public final String SKU_STOCK_SEMAPHORE = "seckill:stock:"; // + 商品随机码

    @Override
    public void uploadSeckillSkuLatest3Days() {
        // 1. 扫描最近三天需要参与秒杀的活动
        R session = couponFeignService.getLatest3DaySession();
        if (session.getCode() == 0) {
            // 上架商品
            List<SeckillSessionWithSkus> sessionData = session.getData(new TypeReference<List<SeckillSessionWithSkus>>() {});
            if (sessionData != null) {
                // 缓存到redis
                // 1. 缓存活动信息
                saveSessionInfos(sessionData);
                // 2. 缓存活动的关联商品信息
                saveSessionSkuInfos(sessionData);
            }
        }
    }

    public List<SeckillSkuRedisTo> blockHandler(BlockException e) {
        log.error("getCurrentSeckillSkus被限流了...");
        return null;
    }

    /**
     * 返回当前时间可以参与的秒杀商品信息
     *
     * blockHandler函数会在原方法被限流/降级/系统保护的时候调用，而fallback函数会针对所有类型的异常。
     */
    @SentinelResource(value = "getCurrentSeckillSkusResource", blockHandler = "blockHandler")
    @Override
    public List<SeckillSkuRedisTo> getCurrentSeckillSkus() {
        // 1. 确定当前时间属于哪个秒杀场次
        long time = new Date().getTime();
        Set<String> keys = redisTemplate.keys(SESSIONS_CACHE_PREFIX + "*");
        for (String key : Objects.requireNonNull(keys)) {
            String replace = key.replace(SESSIONS_CACHE_PREFIX, "");
            String[] s = replace.split("_");
            long start = Long.parseLong(s[0]);
            long end = Long.parseLong(s[1]);
            if (time >= start && time <= end) {
                // 2. 获取这个秒杀场次需要的所有商品信息
                List<String> range = redisTemplate.opsForList().range(key, 0, -1);
                if (range != null) {
                    BoundHashOperations<String, String, String> hashOps = redisTemplate.boundHashOps(SKUKILL_CACHE_PREFIX);
                    List<String> list = hashOps.multiGet(range);
                    if (list != null) {
                        return list.stream().map(item -> JSON.parseObject(item, SeckillSkuRedisTo.class)).collect(Collectors.toList());
                    }
                    break;
                }
            }
        }
        return null;
    }

    @Override
    public SeckillSkuRedisTo getSkuSeckillInfo(Long skuId) {
        // 1. 找到所有需要参与秒杀的商品的key
        BoundHashOperations<String, String, String> hashOps = redisTemplate.boundHashOps(SKUKILL_CACHE_PREFIX);
        Set<String> keys = hashOps.keys();
        if (keys != null && keys.size() > 0) {
            String regx = "\\d_" + skuId;
            for (String key : keys) {
                // 6_4
                if (Pattern.matches(regx, key)) {
                    String json = hashOps.get(key);
                    SeckillSkuRedisTo skuRedisTo = JSON.parseObject(json, SeckillSkuRedisTo.class);
                    // 随机码
                    if (skuRedisTo != null) {
                        long current = new Date().getTime();
                        if (current < skuRedisTo.getStartTime() || current > skuRedisTo.getEndTime()) {
                            skuRedisTo.setRandomCode(null);
                        }
                    }
                    return skuRedisTo;
                }
            }
        }
        return null;
    }

    // todo 上架秒杀商品的时候，每一个数据都有过期时间。
    // todo 秒杀后续的流程，简化了收货地址等信息
    @Override
    public String kill(String killId, String key, Integer num) {
        long s1 = System.currentTimeMillis();
        MemberRespVo respVo = LoginUserInterceptor.loginUser.get();
        // 1. 获取当前秒杀商品的详细信息
        BoundHashOperations<String, String, String> hashOps = redisTemplate.boundHashOps(SKUKILL_CACHE_PREFIX);
        String json = hashOps.get(killId);
        if (!StringUtils.isEmpty(json)) {
            SeckillSkuRedisTo redis = JSON.parseObject(json, SeckillSkuRedisTo.class);
            // 1. 校验时间的合法性
            long time = new Date().getTime();
            Long endTime = redis.getEndTime();
            long ttl = endTime - time;
            if (time >= redis.getStartTime() && time <= endTime) {
                // 2. 校验随机码和商品id
                String randomCode = redis.getRandomCode();
                String skuId = redis.getPromotionSessionId() + "_" + redis.getSkuId();
                if (randomCode.equals(key) && killId.equals(skuId)) {
                    // 3. 验证购物数量是否合理
                    if (num <= redis.getSeckillLimit()) {
                        // 4. 验证这个人是否已经购买过。幂等性，如果只要秒杀成功，就去占位。 userId_sessionId_skuId
                        String redisKey = respVo.getId() + "_" + skuId;
                        // 自动过期
                        Boolean aBoolean = redisTemplate.opsForValue().setIfAbsent(redisKey, num.toString(), ttl, TimeUnit.MILLISECONDS);
                        if (Boolean.TRUE.equals(aBoolean)) {
                            // 占位成功说明从来没有买过
                            RSemaphore semaphore = redissonClient.getSemaphore(SKU_STOCK_SEMAPHORE + randomCode);
                            boolean b = semaphore.tryAcquire(num);
                            if (b) {
                                // 秒杀成功
                                // 快速下单，发送MQ消息
                                String timeId = IdWorker.getTimeId();

                                SeckillOrderTo orderTo = new SeckillOrderTo();
                                orderTo.setOrderSn(timeId);
                                orderTo.setMemberId(respVo.getId());
                                orderTo.setNum(num);
                                orderTo.setPromotionSessionId(redis.getPromotionSessionId());
                                orderTo.setSkuId(redis.getSkuId());
                                orderTo.setSeckillPrice(redis.getSeckillPrice());
                                rabbitTemplate.convertAndSend("order-event-exchange", "order.seckill.order", orderTo);
                                long s2 = System.currentTimeMillis();
                                log.info("耗时..."+ (s2 - s1));
                                return timeId;
                            }
                        }
                    }
                }
            }
        }
        return null;
    }

    private void saveSessionInfos(List<SeckillSessionWithSkus> sessions) {
        sessions.forEach(session -> {
            long startTime = session.getStartTime().getTime();
            long endTime = session.getEndTime().getTime();
            String key = SESSIONS_CACHE_PREFIX + startTime + "_" + endTime;
            // 缓存活动信息
            if (Boolean.FALSE.equals(redisTemplate.hasKey(key))){
                List<String> collect = session.getRelationSkus().stream().map(item -> item.getPromotionSessionId() + "_" + item.getSkuId()).collect(Collectors.toList());
                redisTemplate.opsForList().leftPushAll(key, collect);
            }
        });
    }

    private void saveSessionSkuInfos(List<SeckillSessionWithSkus> sessions) {
        sessions.forEach(session -> {
            // 准备hash操作
            BoundHashOperations<String, Object, Object> ops = redisTemplate.boundHashOps(SKUKILL_CACHE_PREFIX);
            session.getRelationSkus().forEach(seckillSkuVo -> {
                // 4. 随机码
                String token = UUID.randomUUID().toString().replace("-", "");

                if (Boolean.FALSE.equals(ops.hasKey(seckillSkuVo.getPromotionSessionId() + "_" + seckillSkuVo.getSkuId()))){
                    // 缓存商品
                    SeckillSkuRedisTo redisTo = new SeckillSkuRedisTo();
                    // 1. sku的基本数据
                    R skuInfo = productFeignService.getSkuInfo(seckillSkuVo.getSkuId());
                    if (skuInfo.getCode() == 0) {
                        SkuInfoVo info = skuInfo.getData("skuInfo", new TypeReference<SkuInfoVo>() {});
                        redisTo.setSkuInfo(info);
                    }
                    // 2. sku的秒杀信息
                    BeanUtils.copyProperties(seckillSkuVo, redisTo);
                    // 3. 设置当前商品的秒杀时间信息
                    redisTo.setStartTime(session.getStartTime().getTime());
                    redisTo.setEndTime(session.getEndTime().getTime());

                    redisTo.setRandomCode(token);
                    String jsonString = JSON.toJSONString(redisTo);
                    ops.put(seckillSkuVo.getPromotionSessionId() + "_" + seckillSkuVo.getSkuId(), jsonString);

                    // 如果当前这个场次的商品的库存信息已经上架就不需要上架
                    // 5. 使用库存作为分布式的信号量  限流
                    RSemaphore semaphore = redissonClient.getSemaphore(SKU_STOCK_SEMAPHORE + token);
                    // 商品可以秒杀的数量作为信号量
                    semaphore.trySetPermits(seckillSkuVo.getSeckillCount());
                }
            });
        });
    }
}
